Vacuum device



Aug. 13, 1968 Filed Aug. 24, 1966 A. Y. MAHE 3,396,548

VACUUM DEVI CE 2 Sheets-Sheet 1 i2 r 1 All [VI/1A INVENTOR. A ND RE Y. MA HE M AGE T A. Y. MAHE Aug. 13, 1968 VACUUM DEVICE 2 Sheets-Sheet 2 Filed Aug. 24, 1966 INVENTOR. AN DRE Y. MA HE A G ENT United States Patent 4 Claims. (c1. 6255.5)

ABSTRACT OF THE DISCLOSURE A vacuum. device with a cooled wall having a helical flow channel with coolant therein in contact with the cooled wall and a receptacle wherein the coolant in said flow channel empties into the receptacle. A second duct communicating with the receptacle whereby the coolant leaves the device.

It is known, in order to obtain a satisfactory vacuum in a space in which operations have to be carried out in high vacuo, to use cold surfaces for condensing residual gas particles at low temperature. Known devices of this kind may, in principle, be constructed in two different ways.

In one embodiment the cold surface is formed by tubes wound in spiralform traversed by the cooling liquid, for example liquid nitrogen. These spirals have the advantage of a large, heat-exchanging surface as compared with the volume, whilst on the outer side due to the forced flow of liquid therethrough a comparatively uniform temperature is maintained. However, this embodiment has the disadvantage that only a small spare quantity of coolant is available, so that at a drop in the supply of coolant the operation is immediately disturbed.

In a second embodiment of a known vacuum device the cold surface is formed by the Walls of vessels for the coolant, which is supplied in the liquid state at the beginning of the operations and the gradual evaporation of which reduces the temperature of the outer walls of said vessels, said walls serving as collecting surfaces for the gas particles to be condensed. The temperature of the walls is, however, not constant, since the liquid level varies in accordance with the rate of evaporation.

Said vessels have furthermore the disadvantage that a large quantity of fluid is required, which has to be replenished in the course of the operations. Moreover, the

volume of the vessels depends upon the surface of the cooled wall required for the condensation of the gas particles, so that an undesirably large space is occupied.

The present invention obviates these disadvantages, and provides a vacuum device having cooled walls and is characterized in that the device comprises a first coolant duct which is in good thermal contact with said wall and in that there is provided a closed vessel, one of the walls of which forms said cooled wall, whilst one end of said coolant duct opens out in the interior of the vessel, which communicates with the surroundings through a second duct.

The coolant passing through the first duct and entering the vessel and subsequently flowing away through the second duct provides a combination of the advantages involved in each of the known embodiments of the known devices, whilst the device according to the invention does not exhibit the disadvantages of said known embodiments.

The invention will now be described more fully with reference to the accompanying drawing.

FIGURE 1 is a cross sectional view of a first embodiment of a device according to the invention, in which ice the collecting surface is fiat; the section is taken on the line 11 in FIGURE 2.

FIGURE 2 is a cross sectional view taken on the line 11-11 in FIGURE 1.

FIGURE 3 is a cross sectional view in an axial direction of a further embodiment, in which the collecting surface is cylindrical.

In the device shown in FIGURES l and 2 the cooled collecting sunface is formed by a fiat, circular plate 1. The surface 2 of the plate 1 is provided with a coolant duct 3, formed by a plurality of co-planar, coils distributed evenly throughout the surface. The duct 3 has a knee 5, the end 9 of which can be taken through the plate 1; said end may be connected with a supply vessel (not shown) for the coolant. The other end 7 of said duct opens out in the interior of the closed vessel 8, which is formed by the plate 1, a cylindrical body 11 and an upper plate 12. A duct 13 traverses the plate 1 and opens out near the upper plate 12, so that a gas or a liquid can flow into the duct 13 through the interstice 14 between the plate 12 and the upper end of the duct 13.

The coolant, which is supplied through the end 9 of the duct 3 to the device, traverses all turns of said duct, so that the plate 1 is cooled by the thermal contact and the outer face 16 of the plate 1 is cooled to an extent such that the residual gas particles in the space comprising the device condense and are fixed thereon. Then the colant flows through the opening 7 of the duct 3 into the vessel 8 and after the latter is filled to a greater or lesser extent, the coolant will leave thedevice at least partly through the duct 13. If desired the liquid flowing off may be resupplied to the duct 3.

The duct 3 is for-med by a tube of a metal of satisfactory thermal conductivity and the thermal contact thereof with the plate 1 is obtained by soldering or welding. The soldering or welding operation is carried out throughout the length of the generatrix of the contact places between the tube and the plate; this 'generatrix is indicated by the broken line 4 in FIGURE 2. The passages of the ducts 3 and 13 through the plate 1 have to be liquid-tight. This tight seal may be obtained advantageously by means of appropriate soldering or welding strips 15 and 6 for the ducts 13 and 3 respectively. The vessel 8 has also to be liquid-tight; the seal is preferably made by soldering or welding the plate 1 to the lower rim of the cylindrical portion 11 of the vessel. The upper plate 12 is integral with the cylindrical portion, for exple by means of flanged connections or in another way. The plate 1 is also made of a material of good thermal conductivity, which has furthermore to be easily solderable.

In a second embodiment as shown in FIGURE 3 the collecting surface is cylindrical and the duct serving for cooling is formed by a helical coil 18, the turns of which are not in contact with each other and are fastened to the outer surface of the cylindrical sleeve 19, the concave inner surface 17 of which forms the collecting face. The number of turns and the distance between them depend, of course, on the dimensions of the sleeve 19.

The spiral 18 has a knee 22, which is taken through the lower part of the sleeve 19. The end is formed by a straight portion 23, which can be connected with a coolant supply (not shown).

The other end of the spiral 18 opens out at 29 in the annular vessel 30, which is formed by a sleeve 19, which is connected in a liquid-tight manner at 24 and 25 with a further sleeve 26, which also has a cylindrical shape and has a sectional area slightly exceeding the outer diameter of the spiral 18; the ends of said sleeve are formed by conical connecting pieces 27 and 28. With the conical portion 28 of the sleeve 26 communicates a duct 31,

3 through the end 32 of which the coolant can leave the device.

The coolant enters the device through the opening 33 of the duct 23 and traverses all turns of the spiral 18 and by thermal contact it cools the sleeve 19 so that the gas particles of the space 34 can condense on the concave face 17. The coolant then flows through the opening 2 9 into the vessel 30 and after the vessel is filled, it passes through the tube 31 and leaves the device through the opening 32, where if desired the liquid can be resupplied to the cycle in the liquid or gaseous state.

The coil Y18 and the sleeve 19 are made of a metal of good thermal conductivity. The thermal contact between the coil 18 and the collecting face 17 may be established by means of a soldering of Welding strip 20 and 21 throughout the length of the generatrix of the contact places between the coil 18 and the sleeve 19.

The connection between the sleeves 19 and 26 is established by means of soldered or welded seals 24 and 25 and the passages 22 of the tubular coil through the sleeve 19 and that of the tube 31 through the conical portion 28 of the sleeve 26 are sealed by soldering or welding.

Other embodiments are possible: the coil may be fastened to the collecting face itself, whilst the reservoir is arranged on the other side of the partition. The coil may have joined turns, so that it may form itself the collecting face provided the turns form a satisfactory liquid-tight joint.

The device according to the invention is accommodated in a vacuum space where the gas particles are most effectively collected in the region located opposite the said cold collecting face. In this region the operations requiring high vacuum can be carried out.

The device according to the invention has the follow ing advantages, obtained by means of the helical ducts and the vessels forming a reservoir:

Uniform temperature throughout the cold collecting surface owing to the direct good thermal contact established by soldering between the coolant duct and the collecting surface,

Maintenance of a uniform, low temperature by the circulation of the coolant,

A small quantity of coolant required,

The possibility of regaining and recycling the coolant at the outlet of the device,

The possibility of adapting the cold collecting surface to the volume of the vacuum space and to the space required for the operations to be carried out,

An adequate spare quantity of coolant for maintaining the satisfactory operation of the collecting face, if the quantity of supplied coolant diminishes, the spare quantity being on the other hand sufficiently small to permit rapid emptying and reheating of the device.

Of course, other embodiments are possible within the scope of this invention.

What is claimed is:

1. A vacuum device comprising a closed receptacle having a first cooled plate on which gas particles are adapted to be condensed and a second cooled plate spaced from said first cooled plate, a first coolant duct passing only through said first cooled plate and in good thermal contact therewith, said first coolant duct being spaced from said second cooled plate, said first coolant duct being provided with an opening into said closed receptacle, and a second duct having an open end in said closed receptacle adjacent to said second cooled plate whereby the overflow of said coolant in said closed receptacle evacuates from the latter through said second duct.

2. A vacuum device as claimed in claim 1 wherein said coolant duct is secured to the side surface of said first cooled plate that is located opposite the side surface of said second cooled plate where said gas particles are condensed.

3. A vacuum device as claimed in claim 1 wherein said receptacle contains a sleeve, said first cooled plate forming the -wall of said sleeve, said coolant duct being in the form of a plurality of co-planar coils secured to said first cooled plate.

4. A vacuum device as claimed in claim 1 wherein said first cooled plate has a cylindrical shape, said closed receptacle having a second spaced cooled wall concentric with said first cooled plate thus forming an annular duct closed at both ends, and a coolant duct in said annular duct in the form of a helical coil secured to said cylindrical first cooled plate.

References Cited UNITED STATES PATENTS 3,144,200 8/1964 Taylor et al 6255.5 3,251,198 5/1966 Cornelius 62451 3,252,291 5/1966 Eder 6255.5 3,279,214 10/1966 Klipping et al. 6255.5

ROBERT A. OLEARY, Primary Examiner. 

